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We introduce several measures of novelty for a scientific article in MEDLINE based on the temporal profiles of its assigned Medical Subject Headings (MeSH). First, temporal profiles for all MeSH terms (and pairs of MeSH terms) were characterized empirically and modelled as logistic growth curves. Second, a paper's novelty is captured by its youngest MeSH (and pairs of MeSH) as measured in years and volume of prior work. Across all papers in MEDLINE published since 1985, we find that individual concept novelty is rare (2.7% of papers have a MeSH ≤ 3 years old; 1.0% have a MeSH ≤ 20 papers old), while combinatorial novelty is the norm (68% have a pair of MeSH ≤ 3 years old; 90% have a pair of MeSH ≤ 10 papers old). Furthermore, these novelty measures exhibit complex correlations with article impact (as measured by citations received) and authors' professional age.
